Uncover the Mysteries of Early Earth!
Step back in time and explore the origins of life with our essential study notes! Perfect for students, researchers, and science buffs, these notes cover:
Early Earth's extreme conditions and primordial oceans
The role of comets, asteroids, and volca...
● Timeframe: Life originated between 3.5 and 3.9 billion years ago.
● Surface Temperature: Ranged from 75°C to 95°C.
● Geography: Earth was covered by a global ocean with no solid land masses.
● Atmospheric Composition:
○ Dominated by methane (CH₄) and ammonia (NH₃), along with water vapor
(H₂O) and higher levels of carbon dioxide (CO₂).
○ No free oxygen (O₂) in the atmosphere, leading to the absence of an ozone
layer.
● Core and Magnetic Field:
○ The inner core was liquid and much hotter than today.
○ The Earth had a weaker magnetic field, exposing it to higher levels of
cosmic and solar radiation.
● Extreme Weather: Frequent electrical storms and other extreme weather events
due to volatile conditions.
Bombardment and Atmospheric Development
● Comets and Asteroids:
○ Bombardment brought water and other essential compounds to Earth.
○ Released gases like methane and ammonia, contributing to the reducing
atmosphere.
Formation of Carbon Compounds
● Reducing Atmosphere:
○ High concentrations of methane and ammonia created a reducing
atmosphere conducive to chemical reactions.
○ Lack of oxygen allowed for the spontaneous formation of simple carbon
compounds.
● Pre-Biotic Chemistry:
○ Formation of simple amino acids and hydrocarbons.
○ These compounds joined to form more complex structures like proteins,
lipids, and nucleic acids.
● Emergence of Life:
○ Complex carbon compounds developed the ability to self-replicate.
○ These compounds eventually became encased in membranes, leading to
the formation of early cells.
Comparison to Present Day
● Current Earth Conditions:
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